Wireless access networks have become a key element of a variety of telecommunications network environments. As to enterprise networks, they provide convenient access to network resources for workers carrying portable computers and mobile handheld devices, and for guests or temporary workers similarly equipped. They also provide a cost-effective alternative to relocating physical Ethernet jacks in environments where facilities are moved or changed frequently. In addition, wireless access points operable with diverse communication/computing devices are becoming ubiquitous in public environments such as, e.g., hotels, airports, restaurants, and coffee shops. With the increase in high-speed Internet access, the use of access point(s) in the users' homes is also envisioned and has started for other applications.
Concomitantly, several developments in the user equipment (UE) arena are also taking place to take advantage of the capabilities offered by wireless access networks. Of particular interest is the integration of cellular phones with the capability to interface with a wireless access network such as a wireless Local Area Network (WLAN). With such “dual mode” devices becoming available, it should be appreciated that some interworking mechanism between the cellular network and WLAN would be required so as to facilitate efficient handover of services from one type of network to the other.
Current GAN specifications provide that a UE device (e.g., a mobile station or MS) may register on a wide area cellular network (WACN) such as a Public Land Mobile Network (PLMN) if it is discovered and allowed according to applicable 3rd Generation Partnership Project (3GPP) standards. Also, the UE device may be allowed to register on a GAN under certain circumstances where there is no WACN connectivity. Additionally, similar network connectivity behavior may be encountered where Unlicensed Mobile Access (UMA) technologies are deployed as well. However, several important issues arise in such a scenario e.g., number plan compatibility, service handover, emergency call routing, just to name a few, especially when connectivity to a PLMN is desired via a GAN or UMA-based access network.